kusmono kusmono | Universitas Gadjah Mada (Yogyakarta) (original) (raw)
Papers by kusmono kusmono
International Journal of Engineering
The effect of frequency of speaker membrane vibration on the grain size of the silica nanoparticl... more The effect of frequency of speaker membrane vibration on the grain size of the silica nanoparticles (SNP) was investigated. SNP was synthesized using the alkaline fusion method under the vibration of the membrane speaker. Variations of membrane vibration used in this research were 0, 50, 100, and 200 Hz. The material compositions, crystal structure, and morphology of the synthesized SNP were characterized using X-ray fluorescence (XRF), X-ray diffraction (XRD), and transmission electron microscopy (TEM), respectively. Meanwhile, its dielectric property was determined using impedance spectroscopy. The results showed that the SNP consisted of 99.35% silica and corresponded to the crystalline structure of quartz silica. The SNP size was decreased with increasing vibration frequencies. The smallest size of SNP (9.04±1.9 nm) was obtained at a frequency of 200 Hz. Moreover, the dielectric constant and dielectric losses were increased with an increase in membrane vibration frequency due to the decrease of SNP size.
![Research paper thumbnail of Effects Of Clay Modification And Compatibilizers On The Mechanical, Morphological, And Thermal Properties Of Polyamide 6/Polypropylene Nanocomposites [TN941. K97 2008 f rb]](https://attachments.academia-assets.com/94083375/thumbnails/1.jpg)
](Nanokomposit yang mengandungi gaulan poliamida 6 (PA6)/polipropilena (PP) PA6/PP (70/30) dan orga... more Nanokomposit yang mengandungi gaulan poliamida 6 (PA6)/polipropilena (PP) PA6/PP (70/30) dan organo-tanah liat (0-10 phr) telah disediakan menggunakan penyebatian leburan. Nanocomposites containing polyamide 6 (PA6)/polypropylene (PP) PA6/PP (70/30) blend and organoclay (0-10 phr) were prepared by melt compounding
In the field of material technology, natural fiber materials are candidates for reinforcement in ... more In the field of material technology, natural fiber materials are candidates for reinforcement in the production of lightweight, high-strength, environment-friendly, economical composites. Hybrid composites are comprised of a variety of reinforcement, fillers, and polymers. The objective of this research was to figure out the effect of clay addition on the mechanical properties of hybrid composites reinforced with woven agel leaf fiber/glass fiber. The materials used included woven agel leaf fiber, glass fiber, clay, Yukalac BQTN 157 type unsaturated polyester resin, and methyl-ethyl ketone peroxide catalyst. Firstly, the woven agel leaf fiber was given an alkaline treatment by submersion in a 4% NaOH solution for 1 hour, then rinsed with clean water and dried in the open air for 48 hours. The composite manufacture process employed 3 sheets of woven agel leaf fiber and 4 sheets of glass fiber sized 25 cm × 20 cm with unsaturated polyester matrix. The manufacture method used was the v...
International Journal of Technology, 2015
Nanocrystalline celluloses (NCCs) were successfully extracted from ramie fibers using chemical pr... more Nanocrystalline celluloses (NCCs) were successfully extracted from ramie fibers using chemical pretreatments followed by hydrochloric acid hydrolysis. The effects of acid concentration and hydrolysis time on the characteristics of NCCs were investigated in this study. Results showed that the optimal hydrolysis conditions were found to be 6 M hydrochloric acid concentration at 45 °C for 70 min. The obtained NCC had a rod like-shape with an average of 8.07 nm in diameter, 158.51 nm in length, 22.37 in aspect ratio, 89.61% in the crystallinity index, and 5.81 nm in crystallite size. The higher crystallinity and thermal stability were exhibited by NCCs compared to both raw fibers and chemically purified cellulose. The hydrolysis time had a significant effect on crystallinity and thermal stability. The crystallinity index and thermal stability of NCCs were obtained to decrease with increasing hydrolysis time.
Composites: Mechanics, Computations, Applications: An International Journal
Paediatrica Indonesiana, 2011
Background Reusing endotracheal tubes (EITs) has been performed in Indonesia with no evidence of ... more Background Reusing endotracheal tubes (EITs) has been performed in Indonesia with no evidence of its safety. Objective To evaluate sterility, as well as the mechanical, surface, and matrix properties of reused EITs following 2 different reprocessing procedures.Methods Reused EITs were cleaned and disinfected, then sterilized by ethylene oxide gas sterilization (group A) or dry heat sterilization (group B). New EITs were used as the standard for comparison. Microbes were identified and microbial counts were determined as colony forming units (CFUs). Evaluation of mechanical properties was perfonned by a Universal Testing machine. All samples underwent tensile and compression tests.Load defonnation curves were recorded from F max and strain at F max. Microstructure analysis was done using Xray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX).Results Positive cultures of commensal bacteria were found in 2/12 samples i...
Sari Pediatri, 2016
Latar belakang. Pemakaian ulang kateter penghisap telah biasa dilakukan di Indonesia, namun sejau... more Latar belakang. Pemakaian ulang kateter penghisap telah biasa dilakukan di Indonesia, namun sejauh inibelum ada penelitian mengenai sterilitas dan keamanannya.Tujuan. Mengevaluasi sterilitas, sifat mekanik, dan permukaan serta kualitas matriks kateter penghisap yangdipakai ulang setelah diproses dengan dua jenis prosedur pengolahan yang berbeda.Metode. Kateter penghisap yang dipakai ulang setelah diproses dan disterilisasi menggunakan gas etilen oksida(EO), atau menggunakan sterilisasi pemanasan kering (kelompok B). Semua sampel dibersihkan dan didesinfeksidengan prosedur yang hampir sama. Kateter penghisap baru dipakai sebagai standar. Mikroba yang tumbuh padamedium kultur diidentifikasi. Semua sampel menjalani uji tarik dan kompresi. Analisis mikrostruktur dilakukandengan menggunakan mikroskop elektron (SEM) dan energi-dispersif spektroskopi sinar-X (EDX).Hasil. Kultur positif bakteri komensal pada 6 di antara 15 sampel pada kelompok A, dan 6 dari 17 sampelpada kelompok B. Terdapa...
The demand of magnets increases with the increasing development of electronic industry in Indones... more The demand of magnets increases with the increasing development of electronic industry in Indonesia, but it was still imported from abroad. While the magnetic materials as iron oxide are quite a lot in Indonesia, one of deposits area of iron sand is Southern coast of Bantul Yogyakarta. The sand contained of the mineral magnetic, these minerals were magnetite (Fe3O4) is black color, maghemite ( -Fe2O3). Mineral magnetite can be developed as a magnet, example of magnetic material for magnetic tape, magnetic speaker, magnet electric motors and others. Iron sand at southern coast of Bantul Yogyakarta is blackish gray color indicates that it contains large amounts of magnetic material. The results of research by using a magnet, average 66.32% of weight attracted to magnet permanent. The results of the separation is carried out by sieving method the largest percentage of 32% at opening size <+212 m. Characterizations of magnetic materials using Vibrating Sample Magnetometer (VSM) and X...
Journal of Failure Analysis and Prevention, 2015
ABSTRACT The paper presents results of failure analysis of a primary superheater tube in a steam ... more ABSTRACT The paper presents results of failure analysis of a primary superheater tube in a steam powerplant boiler. The boiler has been in service for around 52,000 h (6 years) and failure occurred on one of the primary superheater tubes in the form of a wide-open burst with appreciable wall thinning. The location of failure was first determined by on-site visual examination. Subsequently, specimens were taken from a region near the fracture surface for chemical analysis, microstructural examination using optical microscopy, and scanning electron microscopy equipped with energy-dispersive X-ray analysis to determine the probable cause of failure; whereas the lifetime of the superheater tubes was assessed using stress rupture test. Results suggest that the cause of failure was overheating due to deposit buildup inside the superheater tube which acted as thermal barrier and wall thinning resulted from direct impingement of flue gases. The lifetime of the superheater tubes is estimated and is discussed in the present investigation.
International Journal of Polymer Science, 2013
Unsaturated polyester (UP)/glass fiber/clay composites were prepared by hand layup method. The ef... more Unsaturated polyester (UP)/glass fiber/clay composites were prepared by hand layup method. The effect of clay loading on the morphological and mechanical properties of UP/glass fiber composites was investigated in this study. X-ray diffraction (XRD) was used to characterize the structure of the composites. The mechanical properties of the composites were determined by tensile, flexural, unnotched Charpy impact and fracture toughness tests. XRD results indicated that the exfoliated structure was found in the composite containing 2 wt% of clay while the intercalated structure was obtained in the composite with 6 wt% of clay. The tensile strength, flexural strength, and flexural modulus of the composites were increased in the presence of clay. The optimum loading of clay in the UP/glass fiber composites was attained at 2 wt%, where the improvement in in tensile strength, flexural strength, and flexural modulus was approximately 13, 21, and 11%, respectively. On the other hand, the high...
eXPRESS Polymer Letters, 2008
Nanocomposites based on polyamide 6/polypropylene (PA6/PP = 70/30) blend containing organophilic ... more Nanocomposites based on polyamide 6/polypropylene (PA6/PP = 70/30) blend containing organophilic montmorillonite (OMMT) and maleated polypropylene (PP-g-MA) as compatibilizer were prepared by melt compounding followed by injection molding. Modification of montmorillonite (MMT) with dodecyalmine was successfully performed. The morphological and mechanical properties of nanocomposites were investigated by using x-ray diffraction (XRD), transmission electron microscopy (TEM), tensile, flexural, and impact tests. The thermal stability of nanocomposites was characterized by using thermogravimetric analysis (TGA) and heat distortion temperature (HDT). XRD and TEM results indicated that the intercalated structure was obtained for PA6/PP/MMT composite, a mixture of intercalated and exfoliated structures for PA6/PP/OMMT nanocomposite, and exfoliated structure for PP-g-MA compatibilized PA6/PP/OMMT nancomposite. Thermal stability and HDT of PA6/PP matrix were improved by the addition of both MMT and OMMT. The introduction of PP-g-MA into the PA6/PP/OMMT nanocomposite enhanced the properties such as stiffness, strength, ductility, impact strength, and HDT. This was attributed to the compatibilizing effect of PP-g-MA which improved interfacial adhesion between OMMT with PA6/PP matrix and also promoted the degree of exfoliation of silicate layers in the PA6/PP matrix.
Case Studies in Engineering Failure Analysis, 2014
Failure of a subsea crude oil API 5L X52 steel pipeline which led to oil leakage has been reporte... more Failure of a subsea crude oil API 5L X52 steel pipeline which led to oil leakage has been reported to occur after 27 years in service. Some leaks were found to form at the bottom of the horizontal API 5L X52 steel pipeline near an elbow section which connected the pipeline to a riser. The present investigation aims to analyze the main cause of failure by conducting standard failure analysis methods including visual examination, chemical and mechanical characterizations, metallurgical examinations using light optical microscopy in combination with scanning electron microscopy (SEM) equipped with energy dispersive X-ray (EDX) analysis and corrosion test using a three-electrode potential technique. Results of this investigation suggest that the cause of failure is electrochemical corrosion combined with mechanical process known as flow-induced corrosion. The failure mechanism is discussed with specific attentions are paid to fluid flow rate and chloride-containing water phase.
International Journal of Polymer Science, 2013
The clay-reinforced epoxy nanocomposite was prepared by the polymerization method. The effect of ... more The clay-reinforced epoxy nanocomposite was prepared by the polymerization method. The effect of clay addition on the mechanical properties of epoxy/clay nanocomposites was studied through tensile, flexural, impact strength, and fracture toughness tests. The morphology and tribology behavior of epoxy/clay nanocomposites were determined by X-ray diffraction (XRD) and wear test, respectively. The wear test was performed to determine the specific abrasion of the nanocomposites. In addition, the water absorption characteristic of the nanocomposites was also investigated in this study. XRD analysis indicated that the exfoliation structure was observed in the epoxy nanocomposites with 3 wt% of clay, while the intercalated structure was shown at 6 wt% of clay. It was found that the addition of clay up to 3 wt% increased the tensile strength, flexural strength, impact strength, and the fracture toughness. On the contrary, the presence of above 3 wt% of clay produced a reverse effect. It cou...
Engineering Failure Analysis, 2014
Radiant tubes made of wrought 25Cr-38Ni-Mo-Ti alloy steel (HPM) have been in-service for 76,500 h... more Radiant tubes made of wrought 25Cr-38Ni-Mo-Ti alloy steel (HPM) have been in-service for 76,500 h as cracking tubes in an ethylene plant and they are expected to provide reliable service for 100,000 h (11.4 years) or more. During service, the tube inner surfaces were operated at temperature in the range of 820-835°C within which thermal cracking process occurred. These aged tubes were assessed to ensure continued safe operation. The assessment of material degradation was carried out using optical microscopy, scanning electron microscopy (SEM) in combination with energy dispersive X-ray (EDX) analysis, X-ray powder diffraction (XRD) analysis, Vickers microhardness measurement and stress rupture test to obtain stress-Larson-Miller parameter (LMP) curves for remaining life prediction. Results showed that microstructural degradation was observed at the inner surface of the radiant tubes marked by the damage of protective oxide film containing Cr 2 O 3 , Fe 2 O 3 and SiO 2. Once this film was removed, carburization occurred and free C atoms involved during cracking of ethylene easily penetrated along austenitic grain boundaries. In addition, carbon diffusion into the tube metal seemed to promote precipitation of Cr 23 C 6 at grain boundaries and within the grains resulting in a sharp increase in hardness. The outer surface of the radiant tubes, on the other hand, was exposed to higher temperature, typically 1040-1100°C during operation and creep damage seemed to be the main cause of material degradation. Based on stress rupture test, the remaining life of the radiant tubes is expected to be 21,107 h (2.4 years) consistent with the design life. In the present investigation, factors affecting creep are discussed.
Engineering Failure Analysis, 2014
Radiant tubes made of wrought 25Cr-38Ni-Mo-Ti alloy steel (HPM) have been in-service for 76,500 h... more Radiant tubes made of wrought 25Cr-38Ni-Mo-Ti alloy steel (HPM) have been in-service for 76,500 h as cracking tubes in an ethylene plant and they are expected to provide reliable service for 100,000 h (11.4 years) or more. During service, the tube inner surfaces were operated at temperature in the range of 820-835°C within which thermal cracking process occurred. These aged tubes were assessed to ensure continued safe operation. The assessment of material degradation was carried out using optical microscopy, scanning electron microscopy (SEM) in combination with energy dispersive X-ray (EDX) analysis, X-ray powder diffraction (XRD) analysis, Vickers microhardness measurement and stress rupture test to obtain stress-Larson-Miller parameter (LMP) curves for remaining life prediction. Results showed that microstructural degradation was observed at the inner surface of the radiant tubes marked by the damage of protective oxide film containing Cr 2 O 3 , Fe 2 O 3 and SiO 2. Once this film was removed, carburization occurred and free C atoms involved during cracking of ethylene easily penetrated along austenitic grain boundaries. In addition, carbon diffusion into the tube metal seemed to promote precipitation of Cr 23 C 6 at grain boundaries and within the grains resulting in a sharp increase in hardness. The outer surface of the radiant tubes, on the other hand, was exposed to higher temperature, typically 1040-1100°C during operation and creep damage seemed to be the main cause of material degradation. Based on stress rupture test, the remaining life of the radiant tubes is expected to be 21,107 h (2.4 years) consistent with the design life. In the present investigation, factors affecting creep are discussed.
International Journal of Engineering
The effect of frequency of speaker membrane vibration on the grain size of the silica nanoparticl... more The effect of frequency of speaker membrane vibration on the grain size of the silica nanoparticles (SNP) was investigated. SNP was synthesized using the alkaline fusion method under the vibration of the membrane speaker. Variations of membrane vibration used in this research were 0, 50, 100, and 200 Hz. The material compositions, crystal structure, and morphology of the synthesized SNP were characterized using X-ray fluorescence (XRF), X-ray diffraction (XRD), and transmission electron microscopy (TEM), respectively. Meanwhile, its dielectric property was determined using impedance spectroscopy. The results showed that the SNP consisted of 99.35% silica and corresponded to the crystalline structure of quartz silica. The SNP size was decreased with increasing vibration frequencies. The smallest size of SNP (9.04±1.9 nm) was obtained at a frequency of 200 Hz. Moreover, the dielectric constant and dielectric losses were increased with an increase in membrane vibration frequency due to the decrease of SNP size.
Nanokomposit yang mengandungi gaulan poliamida 6 (PA6)/polipropilena (PP) PA6/PP (70/30) dan orga... more Nanokomposit yang mengandungi gaulan poliamida 6 (PA6)/polipropilena (PP) PA6/PP (70/30) dan organo-tanah liat (0-10 phr) telah disediakan menggunakan penyebatian leburan. Nanocomposites containing polyamide 6 (PA6)/polypropylene (PP) PA6/PP (70/30) blend and organoclay (0-10 phr) were prepared by melt compounding
In the field of material technology, natural fiber materials are candidates for reinforcement in ... more In the field of material technology, natural fiber materials are candidates for reinforcement in the production of lightweight, high-strength, environment-friendly, economical composites. Hybrid composites are comprised of a variety of reinforcement, fillers, and polymers. The objective of this research was to figure out the effect of clay addition on the mechanical properties of hybrid composites reinforced with woven agel leaf fiber/glass fiber. The materials used included woven agel leaf fiber, glass fiber, clay, Yukalac BQTN 157 type unsaturated polyester resin, and methyl-ethyl ketone peroxide catalyst. Firstly, the woven agel leaf fiber was given an alkaline treatment by submersion in a 4% NaOH solution for 1 hour, then rinsed with clean water and dried in the open air for 48 hours. The composite manufacture process employed 3 sheets of woven agel leaf fiber and 4 sheets of glass fiber sized 25 cm × 20 cm with unsaturated polyester matrix. The manufacture method used was the v...
International Journal of Technology, 2015
Nanocrystalline celluloses (NCCs) were successfully extracted from ramie fibers using chemical pr... more Nanocrystalline celluloses (NCCs) were successfully extracted from ramie fibers using chemical pretreatments followed by hydrochloric acid hydrolysis. The effects of acid concentration and hydrolysis time on the characteristics of NCCs were investigated in this study. Results showed that the optimal hydrolysis conditions were found to be 6 M hydrochloric acid concentration at 45 °C for 70 min. The obtained NCC had a rod like-shape with an average of 8.07 nm in diameter, 158.51 nm in length, 22.37 in aspect ratio, 89.61% in the crystallinity index, and 5.81 nm in crystallite size. The higher crystallinity and thermal stability were exhibited by NCCs compared to both raw fibers and chemically purified cellulose. The hydrolysis time had a significant effect on crystallinity and thermal stability. The crystallinity index and thermal stability of NCCs were obtained to decrease with increasing hydrolysis time.
Composites: Mechanics, Computations, Applications: An International Journal
Paediatrica Indonesiana, 2011
Background Reusing endotracheal tubes (EITs) has been performed in Indonesia with no evidence of ... more Background Reusing endotracheal tubes (EITs) has been performed in Indonesia with no evidence of its safety. Objective To evaluate sterility, as well as the mechanical, surface, and matrix properties of reused EITs following 2 different reprocessing procedures.Methods Reused EITs were cleaned and disinfected, then sterilized by ethylene oxide gas sterilization (group A) or dry heat sterilization (group B). New EITs were used as the standard for comparison. Microbes were identified and microbial counts were determined as colony forming units (CFUs). Evaluation of mechanical properties was perfonned by a Universal Testing machine. All samples underwent tensile and compression tests.Load defonnation curves were recorded from F max and strain at F max. Microstructure analysis was done using Xray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX).Results Positive cultures of commensal bacteria were found in 2/12 samples i...
Sari Pediatri, 2016
Latar belakang. Pemakaian ulang kateter penghisap telah biasa dilakukan di Indonesia, namun sejau... more Latar belakang. Pemakaian ulang kateter penghisap telah biasa dilakukan di Indonesia, namun sejauh inibelum ada penelitian mengenai sterilitas dan keamanannya.Tujuan. Mengevaluasi sterilitas, sifat mekanik, dan permukaan serta kualitas matriks kateter penghisap yangdipakai ulang setelah diproses dengan dua jenis prosedur pengolahan yang berbeda.Metode. Kateter penghisap yang dipakai ulang setelah diproses dan disterilisasi menggunakan gas etilen oksida(EO), atau menggunakan sterilisasi pemanasan kering (kelompok B). Semua sampel dibersihkan dan didesinfeksidengan prosedur yang hampir sama. Kateter penghisap baru dipakai sebagai standar. Mikroba yang tumbuh padamedium kultur diidentifikasi. Semua sampel menjalani uji tarik dan kompresi. Analisis mikrostruktur dilakukandengan menggunakan mikroskop elektron (SEM) dan energi-dispersif spektroskopi sinar-X (EDX).Hasil. Kultur positif bakteri komensal pada 6 di antara 15 sampel pada kelompok A, dan 6 dari 17 sampelpada kelompok B. Terdapa...
The demand of magnets increases with the increasing development of electronic industry in Indones... more The demand of magnets increases with the increasing development of electronic industry in Indonesia, but it was still imported from abroad. While the magnetic materials as iron oxide are quite a lot in Indonesia, one of deposits area of iron sand is Southern coast of Bantul Yogyakarta. The sand contained of the mineral magnetic, these minerals were magnetite (Fe3O4) is black color, maghemite ( -Fe2O3). Mineral magnetite can be developed as a magnet, example of magnetic material for magnetic tape, magnetic speaker, magnet electric motors and others. Iron sand at southern coast of Bantul Yogyakarta is blackish gray color indicates that it contains large amounts of magnetic material. The results of research by using a magnet, average 66.32% of weight attracted to magnet permanent. The results of the separation is carried out by sieving method the largest percentage of 32% at opening size <+212 m. Characterizations of magnetic materials using Vibrating Sample Magnetometer (VSM) and X...
Journal of Failure Analysis and Prevention, 2015
ABSTRACT The paper presents results of failure analysis of a primary superheater tube in a steam ... more ABSTRACT The paper presents results of failure analysis of a primary superheater tube in a steam powerplant boiler. The boiler has been in service for around 52,000 h (6 years) and failure occurred on one of the primary superheater tubes in the form of a wide-open burst with appreciable wall thinning. The location of failure was first determined by on-site visual examination. Subsequently, specimens were taken from a region near the fracture surface for chemical analysis, microstructural examination using optical microscopy, and scanning electron microscopy equipped with energy-dispersive X-ray analysis to determine the probable cause of failure; whereas the lifetime of the superheater tubes was assessed using stress rupture test. Results suggest that the cause of failure was overheating due to deposit buildup inside the superheater tube which acted as thermal barrier and wall thinning resulted from direct impingement of flue gases. The lifetime of the superheater tubes is estimated and is discussed in the present investigation.
International Journal of Polymer Science, 2013
Unsaturated polyester (UP)/glass fiber/clay composites were prepared by hand layup method. The ef... more Unsaturated polyester (UP)/glass fiber/clay composites were prepared by hand layup method. The effect of clay loading on the morphological and mechanical properties of UP/glass fiber composites was investigated in this study. X-ray diffraction (XRD) was used to characterize the structure of the composites. The mechanical properties of the composites were determined by tensile, flexural, unnotched Charpy impact and fracture toughness tests. XRD results indicated that the exfoliated structure was found in the composite containing 2 wt% of clay while the intercalated structure was obtained in the composite with 6 wt% of clay. The tensile strength, flexural strength, and flexural modulus of the composites were increased in the presence of clay. The optimum loading of clay in the UP/glass fiber composites was attained at 2 wt%, where the improvement in in tensile strength, flexural strength, and flexural modulus was approximately 13, 21, and 11%, respectively. On the other hand, the high...
eXPRESS Polymer Letters, 2008
Nanocomposites based on polyamide 6/polypropylene (PA6/PP = 70/30) blend containing organophilic ... more Nanocomposites based on polyamide 6/polypropylene (PA6/PP = 70/30) blend containing organophilic montmorillonite (OMMT) and maleated polypropylene (PP-g-MA) as compatibilizer were prepared by melt compounding followed by injection molding. Modification of montmorillonite (MMT) with dodecyalmine was successfully performed. The morphological and mechanical properties of nanocomposites were investigated by using x-ray diffraction (XRD), transmission electron microscopy (TEM), tensile, flexural, and impact tests. The thermal stability of nanocomposites was characterized by using thermogravimetric analysis (TGA) and heat distortion temperature (HDT). XRD and TEM results indicated that the intercalated structure was obtained for PA6/PP/MMT composite, a mixture of intercalated and exfoliated structures for PA6/PP/OMMT nanocomposite, and exfoliated structure for PP-g-MA compatibilized PA6/PP/OMMT nancomposite. Thermal stability and HDT of PA6/PP matrix were improved by the addition of both MMT and OMMT. The introduction of PP-g-MA into the PA6/PP/OMMT nanocomposite enhanced the properties such as stiffness, strength, ductility, impact strength, and HDT. This was attributed to the compatibilizing effect of PP-g-MA which improved interfacial adhesion between OMMT with PA6/PP matrix and also promoted the degree of exfoliation of silicate layers in the PA6/PP matrix.
Case Studies in Engineering Failure Analysis, 2014
Failure of a subsea crude oil API 5L X52 steel pipeline which led to oil leakage has been reporte... more Failure of a subsea crude oil API 5L X52 steel pipeline which led to oil leakage has been reported to occur after 27 years in service. Some leaks were found to form at the bottom of the horizontal API 5L X52 steel pipeline near an elbow section which connected the pipeline to a riser. The present investigation aims to analyze the main cause of failure by conducting standard failure analysis methods including visual examination, chemical and mechanical characterizations, metallurgical examinations using light optical microscopy in combination with scanning electron microscopy (SEM) equipped with energy dispersive X-ray (EDX) analysis and corrosion test using a three-electrode potential technique. Results of this investigation suggest that the cause of failure is electrochemical corrosion combined with mechanical process known as flow-induced corrosion. The failure mechanism is discussed with specific attentions are paid to fluid flow rate and chloride-containing water phase.
International Journal of Polymer Science, 2013
The clay-reinforced epoxy nanocomposite was prepared by the polymerization method. The effect of ... more The clay-reinforced epoxy nanocomposite was prepared by the polymerization method. The effect of clay addition on the mechanical properties of epoxy/clay nanocomposites was studied through tensile, flexural, impact strength, and fracture toughness tests. The morphology and tribology behavior of epoxy/clay nanocomposites were determined by X-ray diffraction (XRD) and wear test, respectively. The wear test was performed to determine the specific abrasion of the nanocomposites. In addition, the water absorption characteristic of the nanocomposites was also investigated in this study. XRD analysis indicated that the exfoliation structure was observed in the epoxy nanocomposites with 3 wt% of clay, while the intercalated structure was shown at 6 wt% of clay. It was found that the addition of clay up to 3 wt% increased the tensile strength, flexural strength, impact strength, and the fracture toughness. On the contrary, the presence of above 3 wt% of clay produced a reverse effect. It cou...
Engineering Failure Analysis, 2014
Radiant tubes made of wrought 25Cr-38Ni-Mo-Ti alloy steel (HPM) have been in-service for 76,500 h... more Radiant tubes made of wrought 25Cr-38Ni-Mo-Ti alloy steel (HPM) have been in-service for 76,500 h as cracking tubes in an ethylene plant and they are expected to provide reliable service for 100,000 h (11.4 years) or more. During service, the tube inner surfaces were operated at temperature in the range of 820-835°C within which thermal cracking process occurred. These aged tubes were assessed to ensure continued safe operation. The assessment of material degradation was carried out using optical microscopy, scanning electron microscopy (SEM) in combination with energy dispersive X-ray (EDX) analysis, X-ray powder diffraction (XRD) analysis, Vickers microhardness measurement and stress rupture test to obtain stress-Larson-Miller parameter (LMP) curves for remaining life prediction. Results showed that microstructural degradation was observed at the inner surface of the radiant tubes marked by the damage of protective oxide film containing Cr 2 O 3 , Fe 2 O 3 and SiO 2. Once this film was removed, carburization occurred and free C atoms involved during cracking of ethylene easily penetrated along austenitic grain boundaries. In addition, carbon diffusion into the tube metal seemed to promote precipitation of Cr 23 C 6 at grain boundaries and within the grains resulting in a sharp increase in hardness. The outer surface of the radiant tubes, on the other hand, was exposed to higher temperature, typically 1040-1100°C during operation and creep damage seemed to be the main cause of material degradation. Based on stress rupture test, the remaining life of the radiant tubes is expected to be 21,107 h (2.4 years) consistent with the design life. In the present investigation, factors affecting creep are discussed.
Engineering Failure Analysis, 2014
Radiant tubes made of wrought 25Cr-38Ni-Mo-Ti alloy steel (HPM) have been in-service for 76,500 h... more Radiant tubes made of wrought 25Cr-38Ni-Mo-Ti alloy steel (HPM) have been in-service for 76,500 h as cracking tubes in an ethylene plant and they are expected to provide reliable service for 100,000 h (11.4 years) or more. During service, the tube inner surfaces were operated at temperature in the range of 820-835°C within which thermal cracking process occurred. These aged tubes were assessed to ensure continued safe operation. The assessment of material degradation was carried out using optical microscopy, scanning electron microscopy (SEM) in combination with energy dispersive X-ray (EDX) analysis, X-ray powder diffraction (XRD) analysis, Vickers microhardness measurement and stress rupture test to obtain stress-Larson-Miller parameter (LMP) curves for remaining life prediction. Results showed that microstructural degradation was observed at the inner surface of the radiant tubes marked by the damage of protective oxide film containing Cr 2 O 3 , Fe 2 O 3 and SiO 2. Once this film was removed, carburization occurred and free C atoms involved during cracking of ethylene easily penetrated along austenitic grain boundaries. In addition, carbon diffusion into the tube metal seemed to promote precipitation of Cr 23 C 6 at grain boundaries and within the grains resulting in a sharp increase in hardness. The outer surface of the radiant tubes, on the other hand, was exposed to higher temperature, typically 1040-1100°C during operation and creep damage seemed to be the main cause of material degradation. Based on stress rupture test, the remaining life of the radiant tubes is expected to be 21,107 h (2.4 years) consistent with the design life. In the present investigation, factors affecting creep are discussed.